Table 2.
Incidence of blood culture-confirmed typhoid fever and protective effectiveness of Vi-TT*
| SA 14-14-2 group | Vi-TT group | Protective effectiveness (%) | Intracluster correlation coefficients | p value | ||
|---|---|---|---|---|---|---|
| Total vaccine protection | n=30 685 | n=30 882 | .. | .. | .. | |
| Typhoid fever | 192 | 29 | .. | .. | .. | |
| Person-years of follow-up | 30 253 | 30 349 | .. | .. | .. | |
| Incidence rate, per 100 000 person-years | 635 (548–731) | 96 (64–137) | 85% (97·5% CI 76 to 91) | 0·0013 | <0·0001 | |
| Overall vaccine protection | n=155 448 | n=155 841 | .. | .. | .. | |
| Typhoid fever | 331 | 144 | .. | .. | .. | |
| Person-years of follow-up | 155 458 | 154 449 | .. | .. | .. | |
| Incidence rate, per 100 000 person-years | 213 (191–237) | 93 (79–110) | 57% (97·5% CI 43 to 68) | 0·0007 | <0·0001 | |
| Indirect vaccine protection | n=134 835 | n=135 110 | .. | .. | .. | |
| Typhoid fever | 139 | 115 | .. | .. | .. | |
| Person-years of follow up | 125 205 | 124 100 | .. | .. | .. | |
| Incidence rate, per 100 000 person-years | 111 (93–131) | 93 (77–111) | 19% (95% CI −12 to 41) | 0·0008 | 0·20 | |
Data are incidence rate (95% CI) or % (95% CI) unless stated otherwise.
*
Protective effectiveness, p values, and CIs were adjusted for the stratifying variables for randomisation, including geographical ward, distance to study clinics, number of eligible children at baseline, and other baseline covariates prespecified in the statistical analysis plan, including age, sex, toilet type in the house, drinking water source, treatment of drinking water, handwashing before meals, and handwashing after defecation. SA 14-14-2=Japanese encephalitis vaccine. Vi-TT=Vi-tetanus toxoid conjugate vaccine.